RV power converter Todd PC40 -- insulator problem

Discussion in 'Electronic Repair' started by Michael Caplan, Sep 24, 2003.

  1. Does anyone have information on or experience with the PC40, 40 amp
    converter made by Todd Engineering Sales of Tucson (now out of business)?
    I'd sure like to get hold of a schematic, but my main interest right now is
    in identifying the special insulator used under the mosfets.

    The power supply is used to provide the 12 DC used in recreational travel
    trailers.

    It's basically three paralleled SMPS's mounted inside a large aluminum heat
    sink (which is also the case), one of which, as far as I can tell, is the
    master.

    The unit came into my shop with no output. After getting the case opened
    (it's all pop-riveted) and pulling out the master board, I found the IRF740
    mosfet on this board shorted and the resistor next to it open (looks like
    0.24 Ohms, 2 Watt -- red, yellow, silver, then gold on a gray body). I
    also found signs of arcing from the mosfet to the heat sink. The arcing
    appears to have been through the mosfet's insulator, and that is where I am
    puzzled.

    The mosfet, an IRF740 in a TO-220 type case, is insulated from the heat sink
    by a piece of what at first looks like a standard silicon rubber heat
    conductive insulator. However, I was attracted to the fact that there is a
    grounding wire soldered to the insulator. On much closer examination I
    confirmed that the insulator has a metallic core ("middle of the sandwich").
    The point where the heat sink was marked by the arcing corresponds to the
    narrow edge of the insulator where the metallic core is now exposed.

    I suspect that the insulator is compromised and should not be reused. But I
    haven't seen this type of insulation material before and was wondering if
    anyone has come across it. Is there a description and trade name for it?
    What about sources?

    Michael Caplan CET
     
    Michael Caplan, Sep 24, 2003
    #1
    1. Advertising

  2. Mike,
    I am working on the same unit. I am trying to find out the part number of U2
    on the main PCB. It is a 3 terminal TO-92 plastic device, it burned up and I
    can not read the markings.. My unit has a standard insulator, no wire
    soldered to it. The main board near the large chassis terminal has a spade
    terminal soldered to the PCB and held in contact with the heatsink with a
    clip. Also do you know if the telephone type connector is required to turn
    the unit on.

    Thanks

    --
    Tony Marsillo
    Nutmeg Repair
    -----------------------------------------------------------------
    "Michael Caplan" <> wrote in message
    news:...
    > Does anyone have information on or experience with the PC40, 40 amp
    > converter made by Todd Engineering Sales of Tucson (now out of business)?
    > I'd sure like to get hold of a schematic, but my main interest right now

    is
    > in identifying the special insulator used under the mosfets.
    >
    > The power supply is used to provide the 12 DC used in recreational travel
    > trailers.
    >
    > It's basically three paralleled SMPS's mounted inside a large aluminum

    heat
    > sink (which is also the case), one of which, as far as I can tell, is the
    > master.
    >
    > The unit came into my shop with no output. After getting the case opened
    > (it's all pop-riveted) and pulling out the master board, I found the

    IRF740
    > mosfet on this board shorted and the resistor next to it open (looks like
    > 0.24 Ohms, 2 Watt -- red, yellow, silver, then gold on a gray body). I
    > also found signs of arcing from the mosfet to the heat sink. The arcing
    > appears to have been through the mosfet's insulator, and that is where I

    am
    > puzzled.
    >
    > The mosfet, an IRF740 in a TO-220 type case, is insulated from the heat

    sink
    > by a piece of what at first looks like a standard silicon rubber heat
    > conductive insulator. However, I was attracted to the fact that there is

    a
    > grounding wire soldered to the insulator. On much closer examination I
    > confirmed that the insulator has a metallic core ("middle of the

    sandwich").
    > The point where the heat sink was marked by the arcing corresponds to the
    > narrow edge of the insulator where the metallic core is now exposed.
    >
    > I suspect that the insulator is compromised and should not be reused. But

    I
    > haven't seen this type of insulation material before and was wondering if
    > anyone has come across it. Is there a description and trade name for it?
    > What about sources?
    >
    > Michael Caplan CET
    >
    >
     
    Tony Marsillo, Oct 6, 2003
    #2
    1. Advertising

  3. Michael Caplan

    Marshcollins

    Joined:
    Sep 5, 2009
    Messages:
    1
    PC40 phone connector

    I have a manual for the PC40 which indicates the phone connector is for a jumper which switches the voltage from 14.1 vdc output to a lower voltage for when you are continuously connected to shore power. Higher voltage with the jumper installed.
     
    Marshcollins, Sep 5, 2009
    #3
  4. Michael Caplan

    timotb

    Joined:
    Oct 29, 2009
    Messages:
    2
    Todd PC30 Charger

    Could someone tell me if I can use the Todd 12 volt 30 amp model PC30 as a full time battery maintainer. Does this unit have the circuitry to shut off and not over charge a battery if always plugged in and connected?
     
    timotb, Oct 29, 2009
    #4
  5. Michael Caplan

    Reitan

    Joined:
    May 5, 2010
    Messages:
    2
    Todd Engineering Sales, Inc. Model PC 40 Power Source

    Sirs,

    I have successfully repaired a Todd Engineering Sales, Inc. Model PC 40 power source. I drew a schmatic diagram and I would be delighted to share that with those of you that would like to have one.

    I found two open 62K ohm resistors that are in parallel in the zener voltage regulator circuit that powers the PWM IC circuit. Also a N channel power MESH MOSFET was bad in one of the PC boards.

    In exchange I am searching for a schmatic diagram to a Todd Engineering Sales, Inc. power source battery charger/ power supply, model PC30B.

    I hope this will be of some help.

    Rodney
     
    Reitan, May 5, 2010
    #5
  6. Michael Caplan

    Reitan

    Joined:
    May 5, 2010
    Messages:
    2
    Sir.

    I has repaired this power supply and I may have some answers to your questions. Please feel free to contact me.

    Rodney
     
    Reitan, May 5, 2010
    #6
  7. Michael Caplan

    pomonabill220

    Joined:
    Jun 8, 2010
    Messages:
    2
    Hello Tony;
    I have a PC30E that my father gave to me (not working... BIG inductor got REAL hot and chared the pcboard) BUT my U2 (a T0-92 package) has SiLR 645 stamped on it. Also, the board is labeled U2 RT2 OT. NOTE also that right next to this device is a long rectangular (about 1/2 inch tall) mechanical thermostat, THAT might be the RT2 OT NOT the SiLR 645,,,, so take note! So it might be a solid state temperature sensor. All three leads are used (traces).
    I hope this helps.
    IF you have a schematic for the PC30E, I would appreciate seeing your work!
    Thanks!
     
    Last edited: Jun 8, 2010
    pomonabill220, Jun 8, 2010
    #7
  8. Michael Caplan

    lambiasow

    Joined:
    Jun 30, 2010
    Messages:
    1
    Does the manual include a schematic?

    can you post the manual to this site?

    Bill


     
    lambiasow, Jun 30, 2010
    #8
  9. Michael Caplan

    pomonabill220

    Joined:
    Jun 8, 2010
    Messages:
    2
    U2 (the TO-92 package) is a "smps startup regulator". It has a max input of 450volts and output of 15 volts for the switcher drive. After the supply starts, a winding on the transformer is used to supply the logic and the U2 is shutoff. The logic supply uses a power resistor to limit current, a diode to rectify and a zener to regulate the 15 volts. My supply had a bad LM393 (dual comparitor) as well, but it would still run. The comparitor is probably used to current limit, or overcurrent protection, or just for voltage selection... havent found out yet.
    It also appears that the mechanical thermostat is for over temp, and the comparitor shuts down the supply if it gets too hot (yeah right!), or turns the fan on. Just a guess as I learn more.
    over temp is kind of a joke... why did the output inductor in mine cook the board and melt the tape wrapped around it then?!?!?! I got mine with the fan frozen!
     
    Last edited: Jun 30, 2010
    pomonabill220, Jun 30, 2010
    #9
  10. Michael Caplan

    berger316

    Joined:
    Jul 7, 2010
    Messages:
    1
    Reitan,

    I am also having issues with my PC40 unit.
    Could you send me a copy of your schematic.

    Thanks.
     
    berger316, Jul 7, 2010
    #10
  11. Michael Caplan

    icabod2

    Joined:
    Jul 8, 2010
    Messages:
    1
    I would love a copy of your schematic please. I have a model PC 45 which I am sure must be similar.
     
    icabod2, Jul 8, 2010
    #11
  12. Michael Caplan

    ROMOAS

    Joined:
    Sep 28, 2010
    Messages:
    1
    please send me a sch and a parts list i have all the parts i need but 2 items i can not identify mine fryed big time but the transformers are ok so i'm just repairing it for fun i have the PC40 thank you
     
    ROMOAS, Sep 28, 2010
    #12
  13. Michael Caplan

    linetrash75

    Joined:
    Oct 20, 2010
    Messages:
    2
    I have a todd engineering PC40 that is not working, the most i,am capable of is checking in ternal fuse. CZould somebody walk me though this or possibly fix it if i shipp it to you.

    Thanks Jed
     
    linetrash75, Oct 20, 2010
    #13
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Tony Marsillo

    Schematic for Todd Engineering Power Supply PC40B

    Tony Marsillo, Sep 26, 2003, in forum: Electronic Repair
    Replies:
    0
    Views:
    1,905
    Tony Marsillo
    Sep 26, 2003
  2. reggie

    Data required for TDK's PC40 material

    reggie, Feb 21, 2008, in forum: Electronic Design
    Replies:
    2
    Views:
    814
    reggie
    Feb 21, 2008
  3. reggie

    max flux density of 250mT for TDK PC40?

    reggie, Feb 21, 2008, in forum: Electronic Design
    Replies:
    14
    Views:
    905
    Eeyore
    Feb 25, 2008
  4. Uwe Hercksen

    Power Supply from TODD Products Corp.

    Uwe Hercksen, Apr 19, 2010, in forum: Electronic Design
    Replies:
    5
    Views:
    1,677
    Uwe Hercksen
    Apr 22, 2010
  5. Pioneer621
    Replies:
    13
    Views:
    4,164
    lascc61
    Mar 12, 2013
Loading...

Share This Page